Tom Clancy was a popular American author of "techno-thrillers", novels of political and military intrigue and complex geopolitical themes mingled with remarkably accurate details of modern high-tech military hardware. He also wrote several highly respected non-fiction guides to military history and hardware. Clancy himself turned 18 as Vietnam War casualties were mounting, but never served in the military. College students were exempt from the military draft, and Clancy studied at Loyola College before becoming an insurance broker.

His first novel, The Hunt For Red October, was published in 1984, and featured Clancy's frequent protagonist, Jack Ryan, a bright, stalwart, and heroic operative for the CIA. Ryan was also central to Clancy's Patriot Games (1987) Clear and Present Danger (1989), The Sum of All Fears (1991), Debt of Honor (1994), Executive Orders (1996), The Bear and the Dragon (2001), and Red Rabbit (2002). Clancy also wrote several novels featuring a different but just as bright, stalwart, and heroic CIA operative, John Clark. Clancy's Clark novels include The Cardinal of the Kremlin (1988), Without Remorse (1993), and Rainbow Six (1998). The latter was written and released to coincide with the video game of the same name.

Ryan and Clark sometimes appeared in each other's books. Several of Clancy's novels were adapted to the big screen, and Ryan has been played by Alec Baldwin, Harrison Ford, Ben Affleck, and Chris Pine, while Clark has been played by Willem Dafoe and Liev Schreiber. Clancy also wrote about Jack Ryan's war hero father and about Ryan's son, Jack Ryan, Jr., a heroic figure in national security crises set a generation in the future.

Clancy's military plotting and scenarios were considered so plausible that his books, fiction and non-fiction, were particularly popular in the US military and intelligence agencies. He was invited to lecture at the Pentagon several times, and Department of Defense officials regularly offered Clancy un-classified background briefings on upcoming weapons projects.

Clancy's fiction took an earnestly favorable view of law enforcement and the U.S. military, and his later novels were more political, allowing the author to voice his generally conservative beliefs. He also spoke out to the media on some issues. In the aftermath of September 11, Clancy appeared on The O'Reilly Factor, and explained why this disaster had happened:

The general difference between conservatives and liberals is that liberals like pretty pictures and conservatives like to build bridges that people can drive across. And conservatives are indeed conservative because if the bridge falls down then people die, whereas the liberals figure, we can always build a nice memorial and make people forget it ever happened and was our fault. They're very good at making people forget it was their fault. All right?

The CIA was gutted by people on the political left who don't like intelligence operations... And as a result of that, as an indirect result of that, we've lost 5,000 citizens last week.

Condoleezza Rice, George W. Bush's National Security Advisor, is apparently not a Clancy fan. She said several times that "No-one could have imagined [terrorists] taking a plane, slamming it into the Pentagon ... [or] into the World Trade Center, using planes as a missile..." But Clancy did. In Debt of Honor, a Japanese kamikaze pilot intentionally crashes an airliner into the U.S. Capitol, killing the President, most of the Senate and House of Representatives, and the entire U.S. Supreme Court. The book, published in 1994, was a huge bestseller, like all of Clancy's fiction.

Clancy was married to Alexandra Llewellyn, first cousin to Colin Powell. Powell actually introduced Clancy to Llewellyn, while Clancy was still happily married to his first wife.

In the 1990s, Clancy started Red Storm Entertainment, a multimedia company specializing in computer games. His name later appeared above several popular video game titles, including Splinter Cell, Ghost Recon, Rogue Spear, and Rainbow Six. Clancy also branded several lines of books with his name -- Tom Clancy's Net Force, Tom Clancy's Op-Center, and Tom Clancy's Power Plays. The books were written and credited to other authors, with plotlines and premises under Clancy's supervision.

He was part owner of the Baltimore Orioles baseball team, and also owned a tank.